B-man - up early!!!
just deciding that a steam rate is good or not good is specultaion, does not Harry have published data on any of his engine tests in his many years of steaming????
reheat only, only, only helps effcy if it is what MechE's call a reversible process - if irreversible really is not that helpful to effcy. --- pulling steam at intermediate presssure and reheating, helps - Cyclone does not do that best I can tell.
FW hetaing can be great but needs to be the reversible type -
one indicator of likely efficient process is to see if the cycle extracts as much usefil/available enrgy as possible in the working fluid and converts to what ever the useful form of energy that is desired - example of poor effcy - incandescent light bulb, goal is light but any heat is not useful (usually damging to the environment around the bulb, incandescent bulb is low effcy - LED, highly efficienct in converting energy to light, very little heat
now steam cycle exhausting at atmospheric is less efficient than at a vaccuum. the steam that is exhausted at atmospheric has remaining energy that could have been used to generate power - if just used for air or feedwater heating, is more irreversible -
lets "test" whether atmospheric is better than vaccuum - if atmospheric better than vaccuum, then, is logical that exhausting at 10 psig over atmospheric would be better, right? and then 20 would be beter than 10 and just exhaust the main steam, that would be best of all??? of course not!!!
yes economics are involved - IC engines use atmosperfic because there is no real pressure 'energy" left, steam cycle always (do not beat me uup with always here - I know of no main stream steam cycle where vac is not important - but am not saying that there are no minor cycles, not well known where vac might not be helpful). do better i.e. are more efficent without a vacuum than with a vaccuum,
inventors have been looking at novel configs for years - and the great conspiracy of the "gods of Rakin" always quash the lowly inventor - bull-feathers - look at novel cycles but get you reversible calcs out so you can quickly assess whther a likely path to effcy or dead-end - lots and lots of dead ends.
as I started, economics often drives how much heat recovery you do, pre-heating combustion air with boiler exhaust probably economical to do, preheating combustion air with remaining temp in condenser, bad thermo so probably not economic
attributes on likely efficient steam engine, multi-stage, reheat between stages, vaccuum condensing, pick good inlet steam temp/press to maximize available enthalpy drop.
thanx
